Electric butt welding



i Feb. 28, 1928. 1,660,425

` T. E. MUR Y, JR

TEQMS @E BEQOXLYN,

t een mancante materne.

.application niet! September i6, that. Serial vsometimes diliiculties in maintaining a perfeet Contact of the electrodes with the work during the forward pressing movement. My invention is directed particularly to the avoidance of such diculties and generally to the securin of a good Contact of the electrodes with t e work. rThe accompanying drawings illustrate embodiments ot the invention.

ldig. l is a sectional view illustrating the welding of tubular articles.

Fig..A 2 is a similar View welding ci plates.

There are a number of tubular products which can be economically made :from sheet metal b bending over the edges of a blank and we ding such edges together.- Examples of such roducts and methods of production are escribed in previous applications of Thomas E. Murray Numbers 509,- 938 and 563,943. Fig. 1 illustrates two such blanks 1, bent around to bring the edges 2 together, and electrodes for pressing such edges together and taking up a certain quantity of the metal while passing a current across the joint. The apparatus 1s shown for working on two blanks at once, but the principle is equally applicable for working on a single blank. A bottom electrode 3 carried in a shoe 4 is grooved to provide seats for the two blanks which are arranged with edges on the inner side, that is adjacent to each other. Two top electrodes 5 are used, one for each blank and shaped with a bearing face 6 engaging the quadrant of the blank near the joint. When such electrodes are pressed forward there is a certain movement of the blank due to the closing of the air gap and the taking up orextrusion of metal at the joint. This involves a change in the shape of blank and a movement there- 0f vwith relation to the electrodes approximately in a circular direction around the center of the blank. If the electrode made a perfect contact at the beginning of the movement, therefore, the contact' at the end would be imperfect and there would be a loss of eieiency. I propose to avoid, or at least to minimize, this diiculty by first illustrating the forcing the electrodes against the blank in' a direction transverse to theadvance of the electrode dur' welding. The electrodes 5 are loosely carried in the top electrode shoe 7 and a wedge 6 is carried by said shoe having coli ue faces bearing on similar 'Laces 9 of the e ectrcdes. The electrodes are connected by deaible leads l0 to the same source ce of welding current and are preferably separated from the shoe by insulating materia il,

New, when' the shoe 7 is pressed downwerd the rst edeet is to press the eleces trcdes 5, against the yielding insulating sheets ll, laterally as well as forward, so that they will grip the blanlr over a wide area. 4It is particularly important in this connection that the lower end of the elec- 70.

trode, nearest the edge of the blank, move laterally to such a position that in the subsequent orward movement the blank will not, by bending further inward, escape the edge of the electrode.

The "invention is particularly useful in connection'with the method o welding described in my re-issue Patent No. 15,466 of. October l0, 1922 in which a current of extremely high am rage is passed across the ,joint for a very rief interval of time, generally a fraction of a second. In such an operation it is important that the electrode engage the work properly in the beginning,

slnce there is very little tlme for adjustment afterwards. in this method of welding also it is particularly important that the electrode engage the work close to the Joint. l

The bottom structure may be made practically a re etition-of that of the top, with two electr es of the same polarity. engaging the two different blanks. Or a single electrode may be used at the bottom, as illustrated, with recesses which lit the ultimate shape of the blank. For a single tube a single one of the electrodes 5 could be used with a bottom electrode which is similarly adjustable laterally; or one of the electrodes may be thus adjustable to avoid sl1p and the other may be fixed a ain'st lateral movement. 100

The pressing of t e upper shoe 7 downward first wed es the electrodes to a good t on the work and second, forces the electrodes down to Yclose the air gap and to press the parts together. The current is then turned on and, the pressure continuing, ,a 'determined quantity of the metal is taken up. The electrode is capable of a slight lateral movement suicient to avoid slipping during the advance `as the shape of the work chan Wiglse the invention is of particular mportance in connection with curved pieces of work, like the portions of the blah-k1 which are to be joined, it is useful also 1n connection with work pieces of other shapes. Fig. l2 shows its application to the butt welding of two plates 12 and 13. The plate 12 is clamped between two sections 14 and 15 of one electrode and the plate 13 between sim ilar sections of an electrode of opposite polarity. Preferably both the parts 14 and 15 are of copper or similar highly conducting material, so as to pass the current to "bothy faces of the work, though in some cases only one of these'parts vneeds to be of such material. The electrodes are clamped and advanced by means of shoes 16 carrying wedges 17 adapted to bear against inclined faces 18 of the electrodes 15. When the parts 16 are advanced the first veffect is a lateral pressing of the electrodes 15 against' the work so as to ensure the closest contact therewith; after which the continued movement of the parts brings the edges of the plates 12 and 13 together and, the welding current being turned on, takes up the parts sutliciently to produce a good welded joint.

Although I have described with great particularity of detail certain embodiments of my invention, yet it is not to be understood therefrom that the invention is resricted to the particulariembodiments disclosed. Various modifications thereof in detail and in the arrangement of the parts may be made by those skilled in the art without departure from the invention as defined in the following claims. s I

What I claim is:

1. In a welding machine of the character described, electrodes adaptedtoengage two pieces of work arranged alongside of each other and mechanism for pressing said electrodes in opposite lateral directions to maintain close engagement with the work while also pressing them forward to take up the joints of the twoworkpieces.

2. In a welding machine of the character assenze 'and pressure of said electrode against the work during the welding operation.

3. In a welding machine of the character described, an electrode adaptedto yield laterally and a forwardly movable part engagin(r said electrode along a line inclined to such fbrward movement to press it laterally and forwardly during the welding operation.

4. In a welding machine of the character described for welding longitudinal joints in a pair of tubes alongside of each other, the combination of forwardly moving means for pressing the parts together at the joint and electrodes which lit the curved faces of the .work and are pressed laterally in opposite directions against the respective tubes by the forward movement of said means.

5. In electric i'rvelding by pressing the parts together between electrodes, the method of advancing an electrode which consists in moving it laterally against the work and forwardly to take up the work, both during a single welding movement of the electrode.

6. The method of electrically welding work pieces which tend to yield laterally when pressed forward, which includes pressing them together between electrodes while passing a current across the joint, forcing the electrodes laterally against the work and forwardly to take up metal at the joint, both during -asingle welding movement of the electrodes.

7. In the electric welding of work having a curved face by pressing the parts together between electrodes, the method of advancing an electrode which consists in moving it laterally into engagement with said face and` forwardly to take up the work, both during a single welding movement of\ the electrode.

In witness whereof, I have hereunto signed i my name.

THOMAS n. MURRAY, JR. 

